[PATCH v6 6/7] reftable: add code to facilitate consistency checks

From

Karthik Nayak <karthik.188@gmail.com>

Date

Oct 7, 2025, 12:11 UTC

Message-ID

<20251007-228-reftable-introduce-consistency-checks-v6-6-638cff42f0b0@gmail.com>

In-Reply-To

<20251007-228-reftable-introduce-consistency-checks-v6-0-638cff42f0b0@gmail.com>

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 Makefile                 |   3 +-
 meson.build              |   1 +
 reftable/fsck.c          | 100 +++++++++++++++++++++++++++++++++++++++++++++++
 reftable/reftable-fsck.h |  40 +++++++++++++++++++
 4 files changed, 143 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 4c95affadb..03fbaf2b21 100644
--- a/Makefile
+++ b/Makefile
@@ -2732,9 +2732,10 @@ XDIFF_OBJS += xdiff/xutils.o
 xdiff-objs: $(XDIFF_OBJS)
 
 REFTABLE_OBJS += reftable/basics.o
-REFTABLE_OBJS += reftable/error.o
 REFTABLE_OBJS += reftable/block.o
 REFTABLE_OBJS += reftable/blocksource.o
+REFTABLE_OBJS += reftable/error.o
+REFTABLE_OBJS += reftable/fsck.o
 REFTABLE_OBJS += reftable/iter.o
 REFTABLE_OBJS += reftable/merged.o
 REFTABLE_OBJS += reftable/pq.o
diff --git a/meson.build b/meson.build
index b3dfcc0497..8914252910 100644
--- a/meson.build
+++ b/meson.build
@@ -452,6 +452,7 @@ libgit_sources = [
   'reftable/error.c',
   'reftable/block.c',
   'reftable/blocksource.c',
+  'reftable/fsck.c',
   'reftable/iter.c',
   'reftable/merged.c',
   'reftable/pq.c',
diff --git a/reftable/fsck.c b/reftable/fsck.c
new file mode 100644
index 0000000000..26b9115b14
--- /dev/null
+++ b/reftable/fsck.c
@@ -0,0 +1,100 @@
+#include "basics.h"
+#include "reftable-fsck.h"
+#include "reftable-table.h"
+#include "stack.h"
+
+static bool table_has_valid_name(const char *name)
+{
+	const char *ptr = name;
+	char *endptr;
+
+	/* strtoull doesn't set errno on success */
+	errno = 0;
+
+	strtoull(ptr, &endptr, 16);
+	if (errno)
+		return false;
+	ptr = endptr;
+
+	if (*ptr != '-')
+		return false;
+	ptr++;
+
+	strtoull(ptr, &endptr, 16);
+	if (errno)
+		return false;
+	ptr = endptr;
+
+	if (*ptr != '-')
+		return false;
+	ptr++;
+
+	strtoul(ptr, &endptr, 16);
+	if (errno)
+		return false;
+	ptr = endptr;
+
+	if (strcmp(ptr, ".ref") && strcmp(ptr, ".log"))
+		return false;
+
+	return true;
+}
+
+typedef int (*table_check_fn)(struct reftable_table *table,
+			      reftable_fsck_report_fn report_fn,
+			      void *cb_data);
+
+static int table_check_name(struct reftable_table *table,
+			    reftable_fsck_report_fn report_fn,
+			    void *cb_data)
+{
+	if (!table_has_valid_name(table->name)) {
+		struct reftable_fsck_info info;
+
+		info.error = REFTABLE_FSCK_ERROR_TABLE_NAME;
+		info.msg = "invalid reftable table name";
+		info.path = table->name;
+
+		return report_fn(&info, cb_data);
+	}
+
+	return 0;
+}
+
+static int table_checks(struct reftable_table *table,
+			reftable_fsck_report_fn report_fn,
+			reftable_fsck_verbose_fn verbose_fn UNUSED,
+			void *cb_data)
+{
+	table_check_fn table_check_fns[] = {
+		table_check_name,
+		NULL,
+	};
+	int err = 0;
+
+	for (size_t i = 0; table_check_fns[i]; i++)
+		err |= table_check_fns[i](table, report_fn, cb_data);
+
+	return err;
+}
+
+int reftable_fsck_check(struct reftable_stack *stack,
+			reftable_fsck_report_fn report_fn,
+			reftable_fsck_verbose_fn verbose_fn,
+			void *cb_data)
+{
+	struct reftable_buf msg = REFTABLE_BUF_INIT;
+	int err = 0;
+
+	for (size_t i = 0; i < stack->tables_len; i++) {
+		reftable_buf_reset(&msg);
+		reftable_buf_addstr(&msg, "Checking table: ");
+		reftable_buf_addstr(&msg, stack->tables[i]->name);
+		verbose_fn(msg.buf, cb_data);
+
+		err |= table_checks(stack->tables[i], report_fn, verbose_fn, cb_data);
+	}
+
+	reftable_buf_release(&msg);
+	return err;
+}
diff --git a/reftable/reftable-fsck.h b/reftable/reftable-fsck.h
new file mode 100644
index 0000000000..007a392cf9
--- /dev/null
+++ b/reftable/reftable-fsck.h
@@ -0,0 +1,40 @@
+#ifndef REFTABLE_FSCK_H
+#define REFTABLE_FSCK_H
+
+#include "reftable-stack.h"
+
+enum reftable_fsck_error {
+	/* Invalid table name */
+	REFTABLE_FSCK_ERROR_TABLE_NAME = 0,
+	/* Used for bounds checking, must be last */
+	REFTABLE_FSCK_MAX_VALUE,
+};
+
+/* Represents an individual error encountered during the FSCK checks. */
+struct reftable_fsck_info {
+	enum reftable_fsck_error error;
+	const char *msg;
+	const char *path;
+};
+
+typedef int reftable_fsck_report_fn(struct reftable_fsck_info *info,
+				    void *cb_data);
+typedef void reftable_fsck_verbose_fn(const char *msg, void *cb_data);
+
+/*
+ * Given a reftable stack, perform consistency checks on the stack.
+ *
+ * If an issue is encountered, the issue is reported to the callee via the
+ * provided 'report_fn'. If the issue is non-recoverable the flow will not
+ * continue. If it is recoverable, the flow will continue and further issues
+ * will be reported as identified.
+ *
+ * The 'verbose_fn' will be invoked to provide verbose information about
+ * the progress and state of the consistency checks.
+ */
+int reftable_fsck_check(struct reftable_stack *stack,
+			reftable_fsck_report_fn report_fn,
+			reftable_fsck_verbose_fn verbose_fn,
+			void *cb_data);
+
+#endif /* REFTABLE_FSCK_H */

-- 
2.51.0